Elastic key for holding rock-drills



(No Model.) I

Gr. M. GITHENS.

ELASTIC KEY FOR HOLDING ROCK DRILLS. No. 426,640. Patented Apr. 29,1890.

UNITED STATES PATENT OFFICE.

GEORGE M. GIT HENS, OF BROOKLYN, NEWV YORK.

ELASTIC KEY FOR HOLDING ROCK DRILLS.

SPECIFICATION forming part of Letters Patent No. 426,640, dated April29, 1890.

Application filed January 24, 1890- Serial No. 337,954. (No model.)

To aZZ whom it may concern.-

Be it known that I, GEORGE M. (humans, a citizen of the United States,residing at Brooklyn, in the county of Kings and State of New York, haveinvented an Improvement in Elastic Keys for Holding Rock-Drills andother Articles, of which the following is a specification.

Rock-drills have been received into a stock and held therein by a key,against which a yoke having nuts at its ends has been pressed byscrewing up the nuts; but it is found in use that the key is liable tobecome bent and convex upon the surface that comes into contact with therock-drill, and a similar difficulty is experienced in holdingothertools, especially where the tool is subjected to sudden concussion orstrain.

My present improved key is adapted to use with stocks or holders inrock-drills already in use or to the holders for other tools, the sizeand shape of my improved key being va ried to suit the circumstances ofits use.

In the drawings, Figure 1 is a section of a drill-stock with my improvedkey in elevation. Fig. 2 is a transverse section of the key anddrill-stock and an elevation of the yoke or loop made use of in clampingthe key to the drill.

The stock or holder A is of any desired size or shape, and in the caseof a rock-drill this stock is usually at the end of the pistonrod, andthe stock or holder is adapted to the reception of the shank or end ofthe drill or tool B, and at one side of the drill or tool B and in thestock A is a mortise for the reception of the key D, and any suitableclamp may be applied to this key. I have, however, shown the yoke Ehaving ,two parallel shanks that passthrough the stock A, and arescrew-threaded for the reception of the nuts F, such nuts F havingcylindrical bases that pass into cylindrical recesses in the stock A, inorder that the length of screw upon the nut may be suiiicient to renderit durable under the constant wear to which the parts are subjected, andthe arched or central portion of the yoke crosses the middle of the keyand bears upon it by the action of the nuts F.

The keys heretofore made use of have either been solid, or in someinstances the surface that is in contact with the drill B has beenslightly concave to cause the key to hear at the end portions thereof onthe drill 5 but a key of this character is liable to become bent,because the principal part of the clamping strain is at the middlethereof, and it is difficult to straighten the key after it hasbecomebent. To obviate these difficulties I make a transverse opening throughthe key, as at 2, the same extending nearly from end to end of the key,and the portion 3 of the key becomes a chord and the portion4. of thekey an arch, the chord uniting the ends of the arch; hence the pressureof the yoke or clamp E upon the center of the arch produces tension uponthe chord 3, and the chord 3 prevents the ends of the arch spreading orelongating, and the chord'3 becomes an elastic bearing-piece against theside of the drill or other tool, and the key is not liable to becomebent under the strain or concussion to which it is subjected, becausethe opening 2 is between the clamping device and the drill, and there isa constant yielding action approximately that of an elliptical spring inthe key itself, so that the slight movement inseparable from the drillunder the rapid concussion to which it is subjected does not tend tobend the key, but only to spring the same, and it is restored by itsresiliency to its normal condition instantly, thus rendering the keymuch more durable and its clamping action more effn cient, and it is notliable to become loose when in use because of the slight spring that isallowed to the parts of the key.

I claim as my invention-- 1. A key for holding drills and other toolsformed of one piece 01": metal and having a transverse opening in themetal and between the surface of the key that bears against the tool,and the screw-yoke or other device that clamps the key toward the tool,whereby the key is rendered elastic, substantially as set forth.

2. The combination, with the drill or tool and the clamping device forholding the same, of an intervening key of one piece of metal with oneside arching and the other straight, there being a transverse opening torender the key elastic, substantially as specified.

Signed by me this 20th day of January, 1890.

GEO. M. GITHENS.

Witnesses GEO. T PINOKNEY, WILLIAM G, Morn

